With the development of information communication technologies, a variety of wireless communication technologies have been developed. Among these technologies, wireless local area network (WLAN) is a technology that Internet access is possible in a wireless way in homes, business or specific service providing areas, using portable terminal such as personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), or the like, based on wireless frequency technologies.
WLAN technologies is created and standardized by the IEEE 802.11 Working Group under IEEE 802 Standard Committee. IEEE 802.11a provides a maximum PHY data rate of 54 Mbps using an 5 GHz unlicensed band. IEEE 802.11b provides a maximum PHY data rate of 11 Mbps by applying a direct sequence spread spectrum (DSSS) modulation at 2.4 GHz. IEEE 802.11g provides a maximum PHY data rate of 54 Mbps by applying orthogonal frequency division multiplexing (OFDM) at 2.4 GHz. IEEE 802.11n provides a PHY data rate of 300 Mbps using two spatial streams and bandwidth of 40 MHz, and provides a PHY data rate of 600 Mbps using four spatial streams and bandwidth of 40 MHz.
As such WLAN technology becomes more prevalent and its applications become more diverse, there is increasing demand for new WLAN technology that can support a higher throughput than IEEE 802.11n. Very high throughput (VHT) WLAN technology, that is one of the IEEE 802.11 WLAN technologies, is proposed to support a data rate of 1 Gbps and higher. IEEE 802.11ac has been developed as a standard for providing VHT in the 5 GHz band, and IEEE 802.11ad has been developed as a standard for providing VHT in the 60 GHz band.
In order for a conventional wireless LAN terminal to connect to an access point (AP), a step of searching for a desired AP, that is, a probe request and probe response step, a detailed network searching step in the searched AP, and a link level authentication and association step in the AP, have to be performed.
Meanwhile, the probe request and probe response step that is used in the step of searching for the AP may request and provide basic information for searching and connection.
However, in environments where a large number of terminals and APs are operating simultaneously, a significantly large number of probe requests and responses are generated. In this case, unnecessary radio channel occupancy may be caused by data with a long length due to a significantly large number of pieces of information in the probe response, and the unnecessary radio channel occupancy deteriorate the channel efficiency.
In addition, when simultaneously retrieving a large number of APs using an service set identifier (SSID) list, there is a problem in that it takes a long time to receive the probe response from the desired APs.